Conventionally, there is known an image reading device including a plurality of line sensors that read light of color components different from one another. The image reading device has a platen glass and a light source that irradiates light to a document. In the platen glass, a plurality of reading lines corresponding to the plurality of line sensors have been set. The plurality of reading lines extend in a main scanning direction and are arranged spaced apart from one another in a sub-scanning direction. On an optical path between the platen glass and the plurality of line sensors, an image forming lens is arranged. Light reflected in the aforementioned document passes through the plurality of reading lines on the platen glass and is led to each line sensor through the image forming lens. Each line sensor converts the received light into an image signal for output. Between the image signals outputted from each line sensor, a position shift occurs due to chromatic aberration of the image forming lens. Therefore, a technology of correcting the image signals outputted from each line sensor on the basis of predetermined correction coefficients has been proposed.
In recent years, with the increased demands for speeding up, an image reading device capable of performing a flow reading operation in addition to a fixed reading operation in which a document is fixed to a platen glass and is read, is spreading. In these two reading operations, since document reading states are different from each other, it has been proposed to independently set the aforementioned correction coefficients in each reading operation (for example, see Patent Literature 1).